Many approaches can be taken in the treatment of cancer. One approach is the use of radiosensitisers along with radiation therapy. This two-pronged approach increases the likelihood of success of the cancer therapy. Radiosensitisers are compounds which when administered to the patient make the tumour more sensitive to radiotherapy or act as an oxygen mimic such that they increase the free radicals available following the ionising radiation. The latter type of compound results in the repair mechanisms within the cell being overwhelmed and cell death occurring.
Radiosensitisers involve time-consuming administration by a specialist, which is expensive for the medical institution involved in the treatment. The radiosensitisers are generally given intravenously or by injection in large fluid volumes that take a significant amount of time to administer and a single dose may involve administration over more than one day. The invasive nature of the administration can lead to multiple puncture sites that are at risk of infection.
Most importantly, administration of the radiosensitiser is distressing to the patient. However, in order to maintain therapeutically effective levels within the tumours radiosensitisers that enhance sensitivity to radiation may be administered on a daily basis. Daily irradiation takes place afterwards. Some cytotoxics that are used as radiosensitisers may be administered less frequently, generally once every 3-4 days or at least once per week (e.g. Cisplatin).
Compared to the administration of the radiosensitiser, irradiation is a relatively simple step. Irradiation often takes place for five days and then the patient has two days off before the cycle is repeated until the course of treatment devised by the patient's clinician is finished. The length of the course of treatment will depend, among other things, upon the patient, the type of cancer and the stage of cancer.
US 2008/0131376 describes low toxicity carborane-containing porphyrin compounds with halide, amine or nitro groups and methods and their use, particularly in boron neutron capture therapy (BNCT), X-ray radiation therapy (XRT) and photodynamic therapy (PDT) for the treatment of tumours of the brain, head and neck and surrounding tissue. Using these carborane-containing porphyrin compounds in methods of tumour imaging and/or diagnosis such as MRI, SPECT or PET is also described.
Daryoush Shahbazi-Gahrouei et al. “Synthesis and Application of New Gadolinium-Porphyrins as Potential MR Imaging Contrast Agents for Cancer Detection in Nude Mice” Iranian Biomedical Journal 5 (2 & 3), pp 87-95 (April and July 2001) discloses the structures of Gd-hematoporphyrin and Gd-tetra-carboranylmethoxyphenyl-porphyrin and notes their selective accumulation in human melanoma xenografts on nude mice. The use of these compounds as a dual probe for MRI and BNCT was suggested.
Kreimann et al. “Biodistribution of a carborane-containing porphyrin as a targeting agent for Boron Neutron Capture Therapy of oral cancer in the hamster cheek pouch” Archives of Oral Biology, Vol. 48, Issue 3, Pages 223-232, March 2003 discloses the use of CuTCPH, a lipophilic, carborane-containing tetraphenylporphyrin, in the hamster oral cancer model and considers its biodistribution after peritoneal administration. Kreimann et al. also suggest that this compound might be useful in BNCT.
WO 2007/050564 describes boron-containing tetraphenylporphyrin compounds for use in BNCT of tumours, radiotherapy of tumours and PDT of tumours.
US 2005/0287073 describes low toxicity carborane-containing 5,10,15,20-tetraphenylporphyrin compounds and methods for their use particularly in BNCT and PDT for the treatment of tumours of the brain, head, neck and surrounding tissue. US 2005/0287073 also describes using these carborane-containing tetraphenylporphyrin compounds in methods of tumour imaging and/or diagnosis such as MRI, SPECT and PET.
US 2008/0233047 describes low toxicity halogenated, carborane-containing 5,10,15,20-tetraphenylporphyrin compounds and methods for their use particularly in BNCT and PDT for the treatment of tumours of the brain, head and neck and surrounding tissue. US 2008/0233047 also describes using these halogenated, carborane-containing tetraphenylporphyrin compounds in methods of tumour imaging and/or diagnosis such as MRI, SPECT and PET.
Further background is described in the following documents:                Miura et al. “Biodistribution and Toxicity of 2,4-Divinyl-nido-o-carboranyldeuteroporphyrin IX in mice” Biochemical Pharmacology, Vol. 43, No. 3, pp 467-476, (1992).        Miura et al. “Synthesis of a Nickel Tetracarbonanylphenylporphyrin for Boron Neutron-Capture Therapy: Biodistribution and Toxicity in Tumour-Bearing Mice” Int. J. Cancer, 68, pp 114-119, (1996).        Miura et al. “Boron Neutron Capture Therapy of a Murine Mammary Carcinoma using a Lipophilic Carboranyltetraphenylporphyrin” Radiation Research, 155, pp 603-610, (2001).        Miura et al. “Synthesis of copper octabromotetracarboranylphenylporphyrin for boron neutron capture therapy and its toxicity and biodistribution in tumour-bearing mice” The British Journal of Radiology, 77, pp 573-580, (2004).        
An object of the present invention is to provide alternative cancer therapy. An aim of certain embodiments is to provide improved therapy in which a compound is used in the treatment of cancer using radiation therapy that will extend the period of time between administrations of the doses of the compound.